Star formation associated with the infrared dust bubble N68

Abstract

We investigated the environment of the infrared dust bubble N68 and searched for evidence of triggered star formation in its surroundings. We performed a multiwavelength study of the nebula with data taken from several large-scale surveys: GLIMPSE, MIPSGAL, IRAS, NVSS, GRS, and JCMT. We analyzed the spectral profile and the distribution of the molecular gas (^{13}CO J = 1 - 0 and J = 3 - 2), and the dust in the environment of the N68. The position-velocity diagram clearly shows that the N68 may be expanding outward. We used two three-color images of the mid-infrared emission to explore the physical environment, and one color-color diagram to investigate the distribution of young stellar objects (YSOs). We found that the 24 \mu m emission is surrounded by the 8.0 \mu m emission. Morphologically, the 1.4 GHz continuum correlates strongly with the 24 \mu m emission, and the ^{13}CO J = 1 - 0 and J = 3 - 2 emissions correlate well with the 8.0 \mu m emission. We investigated two compact cores located at the shell of the N68. The spectral intensity ratios of ^{13}CO J = 3 - 2 to J = 1 - 0 range from 5 to 0.3. In addition, young star objects, masers, IRAS, and UC HII regions distribute at the shell of bubble. The active region may be triggered by the expanding of the bubble N68.